There are now eight people in Massachusetts who have tested positive for coronavirus-caused COVID-19, including three new cases in Boston, Gov. Charlie Baker and Boston Mayor Martin Walsh announced Friday afternoon.

The five new positive tests announced Friday more than doubled the previous number of positive tests in Massachusetts. All five people – three who live in Boston and two who live in Norfolk County – attended a Biogen leadership meeting at the Boston Marriott Long Wharf last week, city and state officials said.

"We are fortunate that Massachusetts is home to world-renowned hospitals and leading health care experts that are planning and preparing our communities and providing us with guidance. The general public in Massachusetts remains at low risk, but we are planning and preparing for the potential for more cases to develop here," Baker said Friday. "I think we all know that this is stressful for people. But health experts have advised that a virus like this is not deadly for the vast majority of people who may get it."

Baker said the risk to the general public "remains low," but state and city leaders said they are preparing for the number of cases to continue to grow in the coming days and weeks.

The four cases in Boston include the one federally-confirmed case involving a UMass Boston student who returned from China in late January and has been in isolation since, and three of the five people who attended last week's Biogen meeting and have tested positive. There are three cases in Norfolk County, including the other two people who attended the Biogen meeting, and the eighth case is a woman in her 60s who lives in Middlesex County.

Local, state and federal officials are cooperating to make information available to residents and coordinate their responses.

On Thursday, public health officials in Tennessee announced that a man who tested positive for the coronavirus-caused COVID-19 respiratory illness there had recently traveled to and from Boston. Officials Friday said that man also attended the leadership meeting at Biogen.

Though the three Boston residents and two Norfolk County residents -- one in their 40s and one in their 50s -- from the Biogen meetings are thought to have become infected with coronavirus while in the city, Martinez said it is important to note that these cases do not meet the criteria for community transmission.

"The source of this transmission is known, and it's connected to a confirmed case of the virus and close contact with that patient," he said. "As a reminder, a close contact [is] someone who's had direct face to face contact within six feet of someone for up to 15 minutes. They've had to have an interaction with the presumptive case within 14 days."

Baker said health experts advise the virus "is not deadly for the vast majority of people who may get it," but decision-makers are still planning for the chance that cases could increase and for the larger risks it may pose to the elderly or those with weakened immune systems.

Officials emphasized the importance of individual-level caution to help prevent further spread of the illness. They repeated what's become a common refrain: everyone should wash hands for at least 20 seconds, cough and sneezing into their elbows, and remain home when sick.

"Every person has a responsibility to play a part in containing coronavirus and other germs by following some simple steps you've already heard before," Baker said.

Walsh stressed the importance of good, accurate information to keep residents from panicking during the outbreak.

"It goes back to getting the accurate information out to people and not causing panic," he said.

Information from State House News Service

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